Cystic fibrosis (CF) animal models have contributed significantly to understanding the mechanism of underlying disease. However, existing CF animal models have their limitations, either because the animal models fail to reproduce human phenotypes or because the animal models have very high maintenance costs and need specialized care. In addition, lacking good ?F508CFTR animal model results in poor understanding the pathogenesis of the most common mutation in CF patients and halts CF drug discovery. Using CRISPR/Cas9 we have developed the first rabbit with the disruption of cystic fibrosis transmembrane conductance regulator (CFTR). Initial work on CFTR knockout rabbits (CFTR-/-) revealed lung pathology that is similar to that in human CF patients. In this application, we will test: Aim 1, generate rabbits carrying ?F508 mutation (CFTR?F508/?F508) in CFTR locus; Aim 2, generate gut-corrected CFTR?F508/?F508 rabbits (TgCFTR-CFTR?F508/?F508); and Aim 3, characterize CFTR?F508/?F508 rabbits. The success of proposed work will provide an animal model for understanding the underlying molecular mechanisms, accelerating CF drug discovery and testing the efficacy of new drugs.